Research On The Parameter Estimation Of Frequency Hopping Signal Based On Time-frequency Analysis

The frequency hopping communication system has more and more extensive applications in the field of military communications because of its strong anti-interference ability and anti interception ability.In the modern electronic warfare battlefield confrontation,to be able to predict the interference and frequency hopping sequences effectively against enemy FH signals,one needs to have intercepted FH signals having ability of blind parameter estimation,so reduce the error at low SNR blind estimation of frequency hopping signal parameter ratio,improve the accuracy of estimation has become a hot topic the current research direction of electronic warfare.In this paper,aiming at the problem that the parameter estimation error of frequency hopping communication signal is large under the traditional time-frequency analysis method under low SNR,the application of the traditional optimization method and other improved time-frequency analysis methods in the parameter estimation of frequency hopping signal is studied.Firstly,the frequency hopping communication system's working principle and characteristics are described,we choose time-frequency analysis technology as the analysis tool,comparative analysis of several traditional time-frequency analysis methods,and introduces the algorithm of parameter estimation of frequency hopping signals in non cooperative communication.The important parameters of frequency hopping signals in non cooperative communication are estimated successfully.For the estimation,according to the literatures in the past to optimize the method,the researchers used method of morphological filtering with general result in low SNR,this paper proposed an optimization method based on adaptive energy threshold denoising and morphology of use,The simulation results show that the optimization method proposed in this paper the hop rate estimation error is less than 0.25at-6dB,time hopping sequence normalized mean square error is less than 0.05Secondly,two improved time-frequency analysis methods are studied in this paper.The paper analyses the characteristics of fuzzy function of frequency hopping signal,the time-frequency analysis for signal conversion to the fuzzy domain,using adaptive fuzzy kernel function based on Simulation in different kernel volume conditions,this method uses the properties of kernel function,can effectively eliminate the interference of cross termsinthe time-frequency distribution,in the nucleus the function of Volume 1 can get minimum estimation error.Then using the method of sparse time-frequency analysis of FH signal time-frequency analysis,a sparse model and two kinds of optimization equation,using the approximate L0 norm sparse optimization method,and proposes a time-frequency filtering through one-dimensional frequency dimension matrix optimization method,the simulation results show that the estimation error of hop rate when-6dB is less than 0.03.Finally,this paper extends the noise environment,because the estimation of frequency hopping signal parameters available in the literatures are mostly for the Gauss noise environment,but in the real battlefield electromagnetic environment,the noise is for Alpha stable distribution model.This paper analyzed the traditional method of limitation in the environment of this kind of noise,and by using the fractional lower order thought and time-frequency analysis method combined with the analysis of the simulation,the results show that the fractional lower order time-frequency analysis method can be more accurately in Alpha stable noise distribution of frequency hopping signal based on fractional,In the fractional lower order number is less than or equal to 0.2 and general signal-to-noise ratio is GSNR ?2 dB,this method is able to accurately estimate the the frequency hopping signal parameters accurately.